Method for brightening textile materials

ABSTRACT

A process for brightening textile materials by treatment with optical brighteners in an aqueous liquor, which comprises using from 20 to 80% by weight, each percentage being based on the sum total of all brightening compounds, of the compound I  
                 
 
of which up to 40 mol % can be present as cis isomer, and also from 80 to 20% by weight of at least one compound II selected from  
                 
and also from 0 to 30% by weight of at least one compound of the general formula III

The present invention relates to a process for brightening textile materials by treatment with optical brighteners in an aqueous liquor, which comprises using from 20 to 80% by weight, each percentage being based on the sum total of all brightening compounds, of the compound I

of which up to 40 mol % can be present as cis isomer, and also from 80 to 20% by weight of at least one compound II selected from

and also from 0 to 30% by weight of at least one compound of the general formula III

where R is selected from C₄-C₁₀-alkyl, in the optional presence of one or more blue or violet shading dyes from the class of the anthraquinones, azo dyes or methine dyes.

Optical brighteners are of immense economic immportance as assistants for the textile industry and for the plastics industry. Numerous compounds are known for their ability to confer a white color on textiles or plastics. However, most of these known compounds also have disadvantages. For instance, compounds of the general formula 1

where for example R¹ and R² may each be for example hydrogen, fluorine, chlorine, phenyl, trifluoromethyl, alkyl or numerous other radicals and where V is selected from

are known from EP 0 023 026 and can be applied at low temperature, but their efficiency is limited in that a lot of product is needed to achieve the desired white effect.

Also known is a process for brightening textiles by treating the textiles with distyrylbenzene compounds which are known for example from CH-A 366 512, CH-A 382 709, CH-A 388 294, CH-A 389 585, CH-A 411 329, CH-A 416 078 and CH-A 465 548. EP-A 0 023 027 and EP-B2 0 030 917 and also the references cited in EP-B2 0 030 917 demonstrate the use of mixtures of two or more dicyanostyrylbenzene compounds for the optical brightening of polyesters.

EP 0 023 026 discloses mixtures of optical brighteners that contain from 0.05 to 0.95 part by weight of one or more compounds of the formula 2 p

where A is a phenyl group substituted by an ortho- or para-cyano group, and also from 0.95 to 0.05 part by weight of one or more other compounds selected from a large multiplicity of other compounds. Preference is given to mixtures of 2 p,o′

with compounds of the general formula 1

where R¹ and R² may each be: hydrogen, fluorine, chlorine, phenyl, trifluoromethyl, C₁-C₉-alkyl, alkoxy, alkylamino and numerous further radicals which are recited at page 2 lines 14-21 and V is as defined above, or with compounds of the formula 3b-4b

where B is a functional group, R¹ and R² are each as defined above, n is an integer, R³ is selected from hydrogen and C₁-C₄-alkoxy, R⁴ is selected from C₁-C₄-alkoxy groups and R⁵ is selected from for example C₁-C₆-alkyl and B is preferably a functional group, or further with compounds of the formulae 5b to 6b

where R⁶ to R¹⁰ are each selected from various groups and V is as defined above.

From this multiplicity of embodiments, Table 2 demonstrates by way of example what are essentially mixtures of 2 p,o′ or other isomers with 3c

and with the following derivatives of 4 b.1 and 4 b.2:

The brighteners thus defined are applied by various methods and provide good CIE whiteness.

EP-A 0 023 028 claims mixtures containing from 0.05 to 0.95 part by weight of a mixture consisting of from 20 to 100% by weight of 2 p,o′

and from 0 to 80% by weight each of the compounds 2 p,p′ and 2 o,o′

and also from 0.05 to 0.95 part by weight of one or more derivatives of the formulae 1a and 3a to 6a, useful as optical brighteners, 1a and 3a to 6a being defined essentially similarly to EP-A 0 023 026.

DE-A 197 32 109 demonstrates the optical brightening of polyamide or polyurethane by mixtures of derivatives of compounds of type 1a

where R¹ and R² are independently H or C₁-C₆-alkyl, A is selected from N and CH and X is selected from

and also from stilbenyl, styryl or imidazolyl, with one or more isomers of 2 or one of the numerous derivatives of 4

or numerous further derivatives, for example with 5 b (see above). By way of example, mixtures are demonstrated inter alia (Examples 19-21) of 1 a.1 with 4 b.1

The mixtures exhibit a synergistic effect with regard to CIE whiteness and also good lightfastness.

EP-A 0 321 393 describes the use of compounds of type 1 b,

where D is a C₁-C₄-alkyl group, and compounds of the formula 2 in brightener dispersions. The compounds of type 1 b or 2 are disclosed either by themselves or as specific mixtures, referred to in the cited reference as mixtures 1 to 6 (pages 6-8). In EP-A 0 321 393 it is stated at page 9 line 18 that it is essential to the invention that the mixture contain a copolymer of 2-vinylpyrrolidone with 3-vinylpropionic acid.

In EP-A 0 682 145 the lightfastness of textiles is improved by treating them with formulations containing a fluorescent UV absorber which absorbs at a wavelength of from 280 to 400 nm and is selected from 4,4′-bistriazinylaminostilbene-2,2′-disulfonic acids, 4,4′-diphenylstilbenes, 4,4′-distyrylbiphenyls, 4-phenyl-4′-benzoxazylstilbenes, stilbenylnaphthotriazoles, 4-styrylstilbenes, coumarins, pyrazolines, naphthalimides, triazinylpyrenes, 2-styrylbenzoxazole or 2-styrylnaphthoxazole derivatives, benzimidazolebenzofurans, oxanilide derivatives and bisbenzoxazol-2-yl and bisbenzimidazol-2-yl derivatives, for example of the formulae 1 c or 1 d (claim 8),

where

-   each R¹⁴ is independently hydrogen or C₁-C₄-alkyl or tert-butyl or     —C(CH₃)₂-phenyl or COO—C₁-C₄-alkyl -   R¹⁵ and R¹⁶ are the same or different and selected from H,     C₁-C₄-alkyl and CH₂—CH₂—OH, -   each R¹⁷ is the same or different and selected from H and SO₃ ⁻ -   X is selected from     and X¹ is selected from

However, lightfastness improvement is usually governed by other factors than play a part in the optical brightening of textiles.

A bright white is of immense economic importance in relation to a very wide variety of products, for example in relation to textiles and in relation to shaped plastics articles. The above-demonstrated numerous mixtures, especially the mixtures demonstrated in the examples of EP-A 0 023 026 and EP-A 0 023 028 and also EP-A 0 682 145, exhibit a white which is frequently not sufficiently bright for demanding customers. Moreover, further performance characteristics have room for improvement. Finally, it is desirable for economic reasons for brighteners to be more efficient in that less brightener is needed to achieve the same or a greater effect.

It is an object of the present invention to provide

-   -   a process for brightening textile materials which provides a         particularly bright white coupled with improved efficiency and         otherwise likewise improved performance characteristics;         formulations for a process for brightening textile materials and     -   uses for the new formulations.

We have found that this object is achieved by the process defined at the beginning.

Textile materials for the purposes of the present invention include fibers, slivers, yarns, threads, wovens, knits, nonwovens and garments composed for example of polyester or polyester blends. The textile materials are preferably composed of synthetic polyesters or of blends containing from 45 to 90% by weight of polyester.

Brightening or optically brightening compounds for the purposes of the present invention are fluorescent compounds which are capable of absorbing in the range from 280 to 400 nm and of emitting at a higher wavelength. Examples include compounds from the class of the stilbenes, distyrylbenzenes, diphenyldistyryls, triazinyls, benzoxazoles, bisbenzoxazoles, bisbenzoxazolylthiophenes, bisbenzoxazolylnaphthalenes, pyrenes, coumarins and naphthaleneperidicarboximides. Brightening or optically brightening compounds shall refer especially to brightening or optically brightening compounds of the formulae I, II and III. Weight percentages shall hereinafter be based on the sum total of the brightening compounds, unless expressly stated otherwise.

The term “aqueous liquors” as used herein also comprehends liquors which, as well as water as main constituent, contain up to 40% by volume of one or more further solvents, for example alcohols such as ethanol. The pH of the liquors used according to the present invention is preferably in the range from 3 to 12 and more preferably in the range from 3 to 8.

The processed defined at the beginning is embodied by treating textile materials with from 20 to 80% and preferably from 20 to 70% by weight and more preferably from 30 to 50% by weight of the compound of the formula I

of which up to 40 mol % may be in the form of the corresponding cis isomer, and also from 80 to 20% by weight of at least one of the compounds II

and also from 0 to 30% by weight of a compound of the general formula III

where R is selected from C₄-C₁₀-alkyl, for example n-butyl, iso-butyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, sec-pentyl, neopentyl, 1,2-dimethylpropyl, isoamyl, n-hexyl, isohexyl, sec-hexyl, n-heptyl, isoheptyl, n-octyl, 2-ethylhexyl, n-nonyl and n-decyl; preference is given to n-butyl and 2-ethylhexyl.

It is preferable, as well as from 20 to 80% by weight of the compound I, to use:

-   from 0 to 30% by weight of a compound of the general formula III and     from 20 to 70% by weight each of at least one of the compounds II     p,o′ or m,p′.

Particular preference is given to using from 20 to 70% by weight of the compound II p,o′ and from 10 to 50% by weight of the compound m,p′

-   as well as from 20 to 70% by weight of the compound I and from 0 to     30% by weight of a compound of the general formula III.

Another particularly preferred embodiment, as well as from 30 to 50% by weight of compound I and from 0 to 30% by weight of a compound of the general formula III, utilizes

-   -   from 30 to 60% by weight of the compound II p,o′,     -   from 10 to 30% by weight of the compound II o,o′ and optionally     -   from 10 to 50% by weight of the compound m,p′.

The compound I is synthesized for example as described in U.S. Pat. No. 2,842,545, U.S. Pat. No. 2,875,089 or U.S. Pat. No. 3,147,253. For the purposes of the present invention, the definition of I also comprehends such isomer mixtures as contain from 0.2 to 40 mol % and preferably fromn 0.7 to 20 mol % of cis isomer. The fraction of cis isomer is determined by spectroscopic or chromatographic methods familiar to one skilled in the art, see for example J. Chromat. 1967, 27 (2), 413-22.

The dicyanostyryl compounds II p,o′, II m,p′, II p,p′ and II o,o′ are used in the form of their trans isomers. They customarily contain from 0.01 to 10 and preferably from 0.1 to 5 mol % of isomers having at least one cis double bond, the fraction of cis isomers being determined by spectroscopic methods known to one skilled in the art. They are readily obtainable from terephthaldicarboxaldehyde and the corresponding cyanobenzyl phosphorylides by a twofold Wittig reaction.

In the practice of the process according to the present invention, it may be advantageous to add one or more blue or violet shading dyes. Useful shading dyes generally belong to the class of disperse dyes and vat dyes. These are customary designations. The Colour Index lists such dyes for example as Disperse Blue or Disperse Violet or Vat Blue or Vat Violet.

Blue dyes from the class of the anthraquinones, azo dyes or methine dyes are particularly suitable.

Dyes from the class of the anthraquinones conform for example to the formulae A 1 to A 4

where

-   Z¹ is C₁-C₁₀-alkyl with or without interruption by 1 or 2 oxygen     atoms in ether function and with or without C₁-C₄-alkoxycarbonyl or     cyano substitution or phenl with or without C₁-C₄-alkoxy, phenyl,     substitution, -   Z² is C₁-C₁₀-alkyl with or without interruption by 1 or 2 oxygen     atoms in ether function and with or without hydroxyl, phenyl or     C₁-C₈-alkoxycarbonyl substitution, -   Z³ is oxygen or N—H, -   Z⁴ is hydrogen, C₁-C₁₀-alkyl with or without interruption by 1 or 2     oxygen atoms in ether function and with or without     C₁-C₄-alkoxycarbonyl or cyano substitution or unsubstituted or     C₁-C₄-alkoxy-substituted phenyl, -   Z⁵ is hydrogen or halogen or CN, -   Z⁶ is hydrogen or nitro, and -   Z⁷ is C₂-C₆-alkylene or phenylene.

The abovementioned dyes are generally known dyes. Dyes of the formula A2 are described for example in U.S. Pat. No. 2,628,963, U.S. Pat. No. 3,835,154, DE-A 12 66 425 or DE-A 20 16 794. Dyes conforming to the formulae A1, A3 and A4 are known for example from K. Venkataraman, “The Chemistry of Synthetic Dyes”, Volume 3, pages 391 to 423, 1970.

Suitable azo dyes are in particular monoazo dyes having a diazo component of the aniline or heterocyclic series and a coupling component of the aniline or heterocyclic series.

Suitable heterocycles from which the diazo components are derived come for example from the class of the aminothiophenes, aminothiazoles, aminoisothiazoles, aminothiadiazoles or aminobenzisothiazoles.

Suitable heterocycles from which the coupling components are derived come for example from the class of the thiazoles or diaminopyridines.

More particularly, such azo dyes conform to one of the formulae B 1 to B 7

where

-   Z⁸ is formyl, cyano, C₁-C₄-alkoxycarbonyl or phenylsulfonyl, -   Z⁹ is hydrogen, halogen, C₁-C₈-alkoxy, phenoxy, C₁-C₆-alkylthio,     phenylthio, C₁-C₄-alkylsulfonyl, phenylsulfonyl, methyl or     unsubstituted or chlorine-, methoxy-, ethoxy- or methyl-substituted     phenyl, -   Z¹⁰ is cyano, C₁-C₆-alkoxycarbonyl with or without interruption by     one or two oxygen atoms in ether function in the alkyl chain,     carbamoyl or mono- or di-C₁-C₄-alkylcarbamoyl, -   Z¹¹ and Z¹² are independently C₁-C₈-alkyl with or without     interruption by from 1 to 3 oxygen atoms in ether function and with     or without hydroxyl, cyano, chlorine, phenyl, C₁-C₆-alkoxy,     C₁-C₆-alkoxycarbonyl, C₁-C₆-alkoxycarbonyloxy or mono- or     di-C₁-C₆-alkylaminocarbonyloxy substitution or C₃-C₄-alkenyl or else     in the case of Z¹¹ but not in the case of Z¹² hydrogen, -   Y¹ is hydrogen, C₁-C₄-alkyl, C₁-C₄-alkoxy, chlorine, bromine or a     radical of the formula —NH—CO—R¹¹, where R¹¹ is C₁-C₄-alkyl with or     without C₁-C₄-alkoxy, cyano, hydroxyl, chlorine or C₁-C₄-alkanoyloxy     substitution or C₂-C₃-alkenyl, -   Y² is hydrogen, C₁-C₄-alkyl or C₁-C₄-alkoxy, -   Z¹³ is unsubstituted or C₁-C₄-alkoxy-substituted C₁-C₄-alkyl,     unsubstituted or C₁-C₄-alkoxy-substituted benzyl, unsubstituted or     chlorine-, methyl-, methoxy- or ethoxy-substituted phenyl, 2-pyridyl     or 3-pyridyl, -   Z¹⁴ is cyano, chlorine or bromine, -   Z¹⁵ is unsubstituted or C₁-C₄-alkoxy- or acetylamino-substituted     thienyl or pyridyl, and -   Z¹⁶ is cyano, chlorine or bromine.

The abovementioned azo dyes are known per se. Dyes of the formulae B1 and B2 are described for example in U.S. Pat. No. 5,283,326 or U.S. Pat. No. 5,145,952. EP-A 0 087 616, EP-A 0 087 677, EP-A 0 121 875, EP-A 0 151 287 and U.S. Pat. No. 4,960,873 disclose dyes of the formula B3. U.S. Pat. No. 5,216,139 discloses dyes of the formula B4. U.S. Pat. No. 5,132,412 discloses dyes of the type of the formula B5. Dyes of the formulae B6 and B7 are described for example in U.S. Pat. No. 3,981,883, DE-A 31 12 427, EP-A 0 064 221 or in Venkataraman “The Chemistry of Synthetic Dyes”, Volume 3, pages 444 to 447, or are obtainable by the methods mentioned therein.

Suitable methine dyes conform for example to the formula C

where

-   Y³ is nitrogen or CH, -   Z¹⁸ is C₁-C₂₀-alkyl with or without substitution and with or without     interruption by one or more oxygen atoms in ether function,     substituted or unsubstituted phenyl or hydroxyl, -   Z¹⁹ is a 5-membered aromatic heterocyclic radical, -   Z²⁰ is hydrogen, cyano, carbamoyl, carboxyl or C₁-C₄-alkoxycarbonyl, -   Z²¹ is oxygen or a radical of the formula C(CN)₂, C(CN)COOZ²³ or     C(COOZ²³)₂, where Z²³ is in each case C₁-C₈-alkyl with or without     interruption by 1 or 2 oxygen atoms in ether function, -   Z²² is hydrogen or C₁-C₄-alkyl.

Substituted alkyl in the formula C may have as substituents for example, unless otherwise stated, phenyl, C₁-C₄-alkylphenyl, C₁-C₄-alkoxyphenyl, halophenyl, C₁-C₈-alkanoyloxy, C₁-C₈-alkylaminocarbonyloxy, C₁-C₂₀-alkoxycarbonyl, C₁-C₂₀-alkoxycarbonyloxy (the alkyl chain in the last two radicals mentioned being optionally interrupted by from 1 to 4 oxygen atoms in ether function and/or substituted by phenyl or phenoxy), halogen, hydroxyl or cyano. The number of substituents in substituted alkyl is generally 1 or 2.

Alkyl radicals appearing in the formula C which are interrupted by oxygen atoms in ether function are preferably, unless otherwise stated, alkyl radicals which are interrupted by from 1 to 4 oxygen atoms and especially by 1 or 2 oxygen atoms in ether function.

Substituted phenyl or pyridyl appearing in the formula C may have as substituents for example C₁-C₈-alkyl, C₁-C₈-alkoxy, halogen, especially chlorine or bromine, or carboxyl. The number of substituents in substituted phenyl or pyridyl is generally from 1 to 3.

Z¹⁹ radicals can be derived for example from components of the pyrrole, thiazole, thiophene or indole series.

Important Z¹⁹ radicals include for example those of the formulae C 1 to C 4

where

-   m is 0 or 1, -   Z²⁴ and Z²⁵ are the same or different and are each independently     hydrogen or C₁-C₂₀-alkyl with or without substitution and with or     without interruption by one or more oxygen atoms in ether function,     substituted or unsubstituted phenyl or combined with the interjacent     nitrogen atom to form a 5- or 6-membered saturated heterocyclic     radical with or without further heteroatoms, -   Z²⁶ is hydrogen, halogen, C₁-C₈-alkyl, unsubstituted or C₁-C₄-alkyl-     or C₁-C₄-alkoxy-substituted phenyl, unsubstituted or C₁-C₄-alkyl- or     C₁-C₄-alkoxy-substituted benzyl, cyclohexyl, thienyl, hydroxyl or     C₁-C₈-monoalkylamino, -   each Z²⁷ is the same or different and independently represents     hydrogen, hydroxyl, unsubstituted or phenyl- or     C₁-C₄-alkylphenyl-substituted C₁-C₈-alkyl, unsubstituted or phenyl-     or C₁-C₄-alkylphenyl-substituted C₁-C₈-alkoxy, C₁-C₈-alkanoylamino,     C₁-C₈-alkylsulfonylamino or mono- or     di-C₁-C₈-alkylaminosulfonylamino, -   Z²⁸ is cyano, carbamoyl, mono- or di-C₁-C₈-alkylcarbamoyl,     C₁-C₈-alkoxycarbonyl or substituted or unsubstituted phenyl, and -   Z²⁹ is halogen, hydrogen, C₁-C₄-alkyl, C₁-C₄-alkoxy,     C₁-C₄-alkylthio, unsubstituted or C₁-C₄-alkyl- or     C₁-C₄-alkoxy-substituted phenyl or thienyl.

Such methine dyes are described for example in prior German patent application DE-A 44 03 083.

Of particular importance is a process wherein the polyester or polyester blends are treated in the presence of one or more blue or violet shading dyes from the class of the anthraquinones, especially those of the formula A.

The process works technically particularly well when practised in the presence of the dye of the formula A 3.1

which is also known under the name C.I. Disperse Violet 28 (61102).

The brightening compounds are used according to the present invention in an amount of from 0.005 to 0.07% and preferably from 0.02 to 0.05% by weight, based on the weight of the textile material to be brightened, and provide a white effect which is the same as or superior to that provided by prior art optically brightening materials.

The amount of blue or violet shading dye used is generally in the range from 0.00005 to 0.02% by weight and preferably in the range from 0.005 to 0.002% by weight, based on the weight of the textile material to be brightened. But the use of the shading dye is not obligatory.

The textile materials are generally brightened by the exhaust process or by the thermosol process.

The exhaust process is carried out from an aqueous liquor mostly at from 90 to 135° C. and usually at around 130° C. In the case of application at above 100° C., an autoclave, a high pressure apparatus or a high pressure machine has to be used. The thermosol process is carried out at atmospheric pressure.

The exhaust process is generally carried out by introducing the textile material to be brightened into an aqueous liquor containing the optically brightening compounds, optionally a blue or violet shading dye or a mixture thereof and optionally additives, for example dispersants, carboxylic acids or alkali donors and whose pH is usually in the range from 3 to 12 and preferably in the range from 3 to 8, at from 10 to 35° C. The liquor ratio (weight ratio of liquor to textile material) is in the range from 3:1 to 40:1 and preferably in the range from 5:1 to 20:1. The bath is then heated over 15-30 minutes to 90-130° C., preferably 95-100° C., and maintained at that temperature for 15-60 minutes. Thereafter, the brightened textile material is rinsed and dried.

In the thermosol process, the textile material to be brightened is customarily pad-mangled with an aqueous liquor containing the optically brightening substances, optionally a blue or violet shading dye or mixtures thereof and optionally additives (see above). The wet pickup is generally in the range from 50 to 100%. Thereafter, the textile material is dried and fixed at from 150 to 200° C. for from 5 to 60 seconds.

The dispersants used are preferably dispersants which are colorless and stable to yellowing at up to 210° C. at least.

Examples of particularly suitable dispersants are anionic or nonionic dispersants, especially anionic or nonionic dispersants from the class of the ethylene oxide adducts with fatty alcohols, higher fatty acids or alkylphenols or ethylenediamine-ethylene oxide-propylene oxide adducts.

Particularly preferred dispersants are alkoxylation products which, based on aliphatic or alkylaromatic hydroxy, amino or aminohydroxy compounds, are commercially available under the brand names Synperonic® and Ukanil®, Dehypon®, Neopol® ethoxylates, Emulan®, Lutensol®, Plurafac® and Pluronic® or Elfapur®. Particular preference is given to alkoxylated phenols. Dispersants which are very particularly preferred are alkoxylated phenols of the general formulae IV and V

where

-   a and b are integers such that -   a is in the range from 0 to 180 and preferably from 0 to 125, -   b is in the range from 20 to 180 and especially from 35 to 125, with     the proviso that b≧a; -   M is an alkali metal, preferably Na or K and more preferably Na; -   d is 0 or 1; -   or mixtures thereof.

The preparation of the compounds IV and V is known and is advantageously effected by reacting the phenols VI and VII respectively

with propylene oxide and subsequent reaction of the adduct with ethylene oxide or by reacting VI and VII respectively with ethylene oxide. It is then possible to completely or partially convert the adducts with chlorosulfonic acid or sulfur trioxide into acid sulfuric esters and for the acid esters obtained to be neutralized with alkalis.

The phenols of the formula VI or VII can be obtained by reacting bisphenol A (2,2-(p,p′-bishydroxydiphenyl)propane) or phenol with respectively 4 or 2 mol of styrene in the presence of an acid as a catalyst. The phenols VI and VII are converted by known methods first with propylene oxide and then with ethylene oxide or only with ethylene oxide in the presence of acidic or alkaline catalysts, for example with NaOCH₃ or with SbCl₅, into the corresponding alkoxylation products IV and V respectively where d=0. The alkoxylation can be effected for example by the process described in U.S. Pat. No. 2,979,528.

The acid sulfuric esters are prepared by reacting the alkoxylation products with chlorosulfonic acid or sulfur trioxide, the amount of chlorosulfonic acid or sulfur trioxide being chosen so as to sulfate all the free hydroxyl groups or only a certain percentage thereof. The latter case gives rise to mixtures of compounds of the formula IV or V which contain free and sulfated hydroxyl groups. For use as surfactants, the as-synthesized acid esters of sulfuric acid are converted into water-soluble salts. Water-soluble salts which are advantageous include the alkali metal salts, for example the sodium or potassium salts. Chlorosulfonic acid requires two equivalents and sulfur trioxide one equivalent of alkaline compound. The alkaline compound used is advantageously aqueous alkali metal hydroxide. A temperature of 70° C. should not be exceeded in the neutralization. The salts obtained can be used in the form of aqueous solutions or else isolated as such and used in solid form.

Preference is given to dispersants IV and V where a is from 0 to on average 2.5, b is on average from 25 to 250 and d is from 0 to on average 0.5. Particular preference is given to dispersants IV and V where a is from 0 to on average 2.5, b is on average from 50 to 100 and d is on average 0.5.

Compounds of the formulae IV and V are known and numerous representatives are described in U.S. Pat. No. 4,218,218 for example.

Additives optionally to be added further include for example the biocides or water retention aids customarily used in the textile industry. Additives optionally to be added further include the copolymers of N-vinylpyrrolidone with 3-vinylpropionic acid which are described in EP-A 0 321 393.

A preferred embodiment of the process utilizes a formulation which, as well as water, contains (each percentage being based on the weight of the formulation) from 1 to 40% by weight and preferably from 3 to 10% by weight of the above-particularized mixture of brightener and shading dye, from 3 to 12% by weight of anionic or nonionic dispersant, from 1 to 15% by weight of copolymers of N-vinylpyrrolidone with vinyl acetate or vinyl propionate or mixtures thereof and from 1 to 25% by weight of further additives (e.g. water retention aids or biocides).

The process of the present invention provides excellent white effects on textile materials not only in the exhaust process but also in the thermosol process. The brightened materials have excellent service fastnesses.

The above-described aqueous liquor may be prepared by separate metering of the individual predispersed optically brightening substances and also of each or every optionally employed shading dye, dispersant and/or other additive.

However, the process of the present invention is preferably carried out by applying optically brightening compounds and optionally one or more of the above-described shading dyes, dispersants and other additives as a formulation. The present invention accordingly further provides formulations comprising from 20 to 80% by weight, each percentage being based on the sum total of all brightening compounds, of the compound I,

-   from 20 to 80% by weight of at least one compound II, -   from 0 to 30% by weight of at least one compound of the formula III -   and also in each case optionally -   one or more blue or violet shading dyes from the class of the     anthraquinones, azo dyes, methine dyes, violanthrones or     indanthrones, -   one or more dispersants, water and further additives.

Formulations according to the present invention generally contain water and (each percentage being based on the weight of the formulation) from 1 to 40% by weight and preferably from 3 to 25% by weight of the above-particularized mixtures of brightened compounds, optionally from 0.001 to 0.1% by weight of shading dye, optionally from 0.5 to 40% by weight of dispersant and also from 5 to 60% by weight and preferably from 5 to 52% by weight of additives.

The present invention further provides for the use of the formulation according to the present invention for brightening textile materials, especially polyester or polyester blends.

The examples hereinbelow illustrate the invention.

GENERAL DESCRIPTION

The isomer distribution was as follows: I trans-cis, 95:5 mol %; II p,o′, II mp′, II o,o′, each above 95 mol % of trans, each determined by ¹H NMR spectroscopy.

1. High-Temperature Exhaust Process

100 liters of a dyebath in an autoclave containing the total concentration of brightening compounds reported in Table 1, which were individually dispersed (“finished”) in water and then added, were entered at 25° C. with 10 kg of polyester fabric. The bath was then heated to 130° C. over 30 minutes and maintained at 130° C. for a further 30 minutes. The fabric was then removed from the bath, rinsed and dried. The optical CIE whiteness was determined for analysis in each case.

Comparative (V) tests each utilized a mixture of 50% by weight of II o,p′ and 50% by weight of 4 b.1

from Table 2 of EP 0 023 026. TABLE 1 Brightening of polyester fabric with various mixtures of optical brightening compounds by the exhaust process Total concen- Brightening compounds tration CIE [% by weight] in white- No. I II p, o′ II m, p′ 4 b.I liquor ness 1.1 45 55 — — 0.02 147 1.2 45 55 — — 0.03 155 1.3 45 55 — — 0.057 166 1.4 45 55 — — 0.077 167 1.5 45 55 — — 0.095 167 1.6 40 40 20 — 0.02 150 1.7 40 40 20 — 0.03 158 1.8 40 40 20 — 0.057 164 1.9 40 40 20 — 0.077 169 1.10 40 40 20 — 0.095 169 V 1.11 — 50 — 50 0.02 145 V 1.12 — 50 — 50 0.03 153 V 1.13 — 50 — 50 0.057 163 V 1.14 — 50 — 50 0.077 163 V 1.15 — 50 — 50 0.095 163

The process of the present invention provides in each case a stronger effect than prior art processes while using a smaller amount of brightening compound. Similarly, the process of the invention achieves a peak brightening effect at lower concentrations of optically brightening substances.

2. Thermosol Process

Inventive examples 2.1 to 2.8 were carried out by pad-mangling polyester fabric at room temperature with an aqueous liquor containing a total of 0.8 g/l of optically brightening compounds of the hereinbelow reported composition. The pH was adjusted to 5.5 with acetic acid. The wet pickup was 60%. The fabric was then dried at 110° C. for 20 s and thereafter fixed for 30 seconds at the temperature shown in Table 2.

The comparative examples V 2.9 to V 2.12 were carried out in a similar fashion, except that 0.8 g/l of liquor was used of a mixture of 50% by weight II o,p′ and 50% by weight of

from Table 2 of EP 0 023 026.

The comparative examples V 2.13 to V 2.16 were carried out similarly to the inventive examples, except that 1.5 g/l of a mixture of 70% by weight of II o,p′ and 30% by weight of II o,o′ was used. TABLE 2 Brightening of polyester fabric with various mixtures of optically brightening compounds by the thermosol process; fixing at different temperatures. Fixing Brightening compounds temp- CIE [% by weight] erature white- No. I II p, o′ II m, p′ II o, o′ 4 b.l [° C.] ness 2.1 45 55 — — — 140 133 2.2 45 55 — — — 150 139 2.3 45 55 — — — 160 142 2.4 45 55 — — — 170 144 2.5 40 40 20 — — 140 135 2.6 40 40 20 — — 150 139 2.7 40 40 20 — — 160 142 2.8 40 40 20 — — 170 143 V 2.9 — 50 — — 50 140 128 V 2.10 — 50 — — 50 150 132 v 2.l1 — 50 — — 50 160 136 v 2.12 — 50 — — 50 170 137 v 2.13 — 70 — 30 — 140 130 V 2.14 — 70 — 30 — 150 135 V 2.15 — 70 — 30 — 160 136 v 2.16 — 70 — 30 — 170 140

The process of the present invention provides a stronger effect at the same fixing temperature using a smaller or the same amount of optically brightening compound. 

1. A process for brightening textile materials by treatment with optical brighteners in an aqueous liquor, which comprises using from 20 to 80% by weight, each percentage being based on the sum total of all brightening compounds, of the compound I

of which up to 40 mol % can be present as cis isomer, and also from 80 to 20% by weight of at least one compound II selected from the group consisting of

and also from 0 to 30% by weight of at least one compound of the general formula III

where R is selected from C₄-C₁₀-alkyl, in the optional presence of one or more blue or violet shading dyes from the class of the anthraquinones, azo dyes or methine dyes.
 2. The process as claimed in claim 1, wherein from 20 to 70% by weight of the compound II p,o′ is used as well as from 20 to 80% by weight of the compound I and from 0 to 30% by weight of a compound of the general formula III.
 3. The process as claimed in claim 1, wherein from 20 to 70% by weight of the compound II m,p′ is used as well as from 20 to 80% by weight of the compound I and from 0 to 30% by weight of a compound of the general formula III.
 4. The process as claimed in claim 1, wherein from 20 to 70% by weight of the compound II p,o′ and from 10 to 50% by weight of the compound II m,p′ are used as well as from 20 to 70% by weight of the compound I and from 0 to 30% by weight of a compound of the general formula III.
 5. The process as claimed in claim 1, wherein from 30 to 60% by weight of the compound II p,o′ and from 10 to 30% by weight of the compound II o,o′ are used as well as from 30 to 60% by weight of the compound I and from 0 to 30% by weight of a compound of the general formula III.
 6. The process as claimed in claim 1, wherein from 20 to 60% by weight of the compound II p,o′, from 10 to 50% by weight of the compound II m,p′ and from 10 to 30% by weight of the compound II o,o′ are used as well as from 20 to 50% by weight of the compound I and from 0 to 30% by weight of a compound of the general formula III.
 7. The process as claimed in claim 1, wherein R is 2-ethylhexyl in the compound III.
 8. The process as claimed in claim 1, wherein from 0.5 to 200% by weight, based on the sum total of all brightening compounds, is additionally used of one or more dispersants.
 9. The process as claimed in claim 1, wherein the textile material is polyester.
 10. The process as claimed in claim 1, wherein the textile material is a blend containing from 45 to 90% by weight of polyester.
 11. A formulation comprising from 20 to 80% by weight, each percentage being based on the sum total of all brightening compounds, of the compound I,

from 20 to 70% by weight of at least one compound II selected from the group consisting of,

from 0 to 30% by weight of at least one compound of the formula III

and also in each case optionally one or more blue or violet shading dyes from the class of the anthraquinones, azo dyes, methine dyes, violanthrones or indanthrones, one or more dispersants, water and further additives.
 12. (canceled)
 13. A method of brightening at least one textile material, said method comprising applying said formulation as claimed in claim 11 to said at least one textile material. 